1. Field of the invention
This invention relates to a method of making an electrowetting device, more particularly to a method of making an electrowetting device including a magnetic ink.
2. Description of the related art
An electrowetting device typically includes a housing and a working liquid that is encapsulated in the housing and that changes its surface tension when an external power source is applied to the working liquid for controlling operation modes of the working liquid. The electrowetting device may be used in applications, such as displays, an optical liquid lens, a biochip, etc.
U.S. patent application publication No. 2012/0073740 discloses a method of making an electrowetting device. The method includes the steps of: (a) forming a surrounding wall on an upper surface of a substrate to define a micro-chamber, the surrounding wall having an inner surface surrounding the micro-chamber and a top surface above the inner surface, the upper surface of the substrate being non-hydrophobic; (b) coating the surrounding wall and the upper surface of the substrate with a hydrophobic coating material; (c) removing a portion of the hydrophobic coating material formed on the top surface of the surrounding wall, thereby exposing the top surface of the surrounding wall; and (d) filling a first liquid and a second liquid, which is immiscible with the first liquid, into the micro-chamber. The first liquid is a colored ink, and the second liquid is an electroconductive solution.
The first liquid is required to be firmly positioned at a predetermined region in the micro-chamber and be covered by the second liquid when the second liquid is introduced therein, so that the electrowetting device can work normally and reliably. However, since the first liquid has a density smaller than that of the second liquid, control of the aforesaid positioning and covering of the first liquid is relatively difficult.